1. Field of the Invention
The present invention relates generally to a latch for securely releasably clamping closures such as access panels and doors of industrial cabinets, electrical equipment enclosures and the like in closed positions. More particularly, the present invention relates to a clamping type latch that has a body which is mountable on a closure, and a pawl that is (1) rotatable relative to the body about a center axis of the body between latched and unlatched positions, and (2) translatable along the center axis of the body for movement between latched and latched-clamped positions to clamp the pawl into engagement with a latch plate or other suitably configured portion of an associated door frame. In preferred practice, the present invention provides a half turn clamping type cabinet latch having a minimum of operating component with the exception that a "primary operating element" is advantageously formed by three inexpensive parts, two of which are identical one with another. The operating components of the latch are easy to assemble and disassemble for service. Moreover, the latch provides a capability for clamping a closure toward a surrounding door frame so that a gasket that is interposed between the closure and the door frame can be compressed as the latch is operated to secure the closure.
2. Prior Art
Clamping type latches of a variety of configurations have been proposed for releasably clamping industrial cabinet closures, access panels, and the like in closed positions relative to surrounding door frames, cabinet structures and the like. Such latches are particularly useful where it is desired (1) to compress a closure sealing gasket that is interposed between peripheral portions of a closure and an associated door frame, (2) to suppress vibration of a closure by clamping it snugly into engagement with a framework that surrounds and defines the opening that is closed by the closure, and/or (3) to provide a tightly closing latch that will compensate for irregularities in manufacturing tolerances or for changes in dimensions due to wear. Examples of several forms of clamping type latches are found in U.S. Pat. No. 4,492,394.
Tool engageable operating heads of a variety of configurations have been proposed for use with latches that have rotatable operating elements. An operating head that is configured to receive an operating tool in the form of an Allen wrench is shown in U.S. Pat. No. 4,413,849. Operating heads that are configured for use with special tools to rotate operating elements of clamping type latches like are disclosed in U.S. Pat. No. 4,369,678 and in U.S. Pat. Nos. Des. 270,229, 270,424, and 270,707.
Some prior proposals utilize pawls that are (1) rotatable relative to a closure mounted body between latched and unlatched orientations, and (2) translatable axially along their rotation axes to effect clamping.
3. The Referenced Parent Case
The invention of the referenced Parent Case addresses a need that, despite prior proposals, long has remained, namely the need for a highly reliable yet simply configured clamping type latch that is mountable on a closure and that has an operating member which, when rotated through a range of about one hundred eighty degrees (a "half turn"), is operable to effect, in sequence, (1) rotation of a pawl about a rotation axis tnrough a range of about a ninety degrees (a "quarter turn") from an unlatched to a latched orientation, followed by (2) translation of the pawl along the rotation axis through a range of travel of about one-fourth of an inch to provide a clamping action that is capable of compressing a door gasket which extends perimetrically about the closure. Furthermore, the invention of the referenced Parent Case addressed other needs that have not been fully addressed by prior proposals including the need ror a latch as described above that has its operating components (i.e., elements that interact to control the movements of the pawl) protectively housed by a latch body, with the operating components being easily removed from the body of the latch for lubrication, service and replacement.